The present invention relates to a process for the simultaneous washing and bleaching of raw native fibers, blends of a plurality thereof or their blends with synthetic fibers, and yams or textile products produced therefrom. Such simultaneous washing and bleaching is the necessary pretreatment prior to the aforementioned fibers, fiber blends and textile products being coloured. The invention further relates to a combination product for carrying out this process.
Textile-forming native vegetable fibers, such as cotton, sisal and jute, and also native animal fibers, such as silk and wool, contain waxes, fats and other animal or vegetable constituents responsible for a yellowish brown colouring of the fiber in the raw state. As a result, not all shades which it is desired to dye are possible, or they are obtained in an unlevel form. When native fibers are blended with synthetic fibers, for example with polyamide, polyester, elastane or others, components which interfere with the dyeing additionally include spin finish oils, for example winding oil or silicone oil, as well as the aforementioned waxes and fats on native fibers.
To remove the aforementioned interfering constituents and also spin finish oils and in addition to oxidatively destroy the yellowish brown colouring, it has hitherto been customary to carry out separate washing and bleaching operations to pretreat the abovementioned fibers, fiber blends and their textile products. The treatment liquors used contain water, H.sub.2 O.sub.2, wetting/washing and emulsifying agents, alkali and bleach regulators/sequestrants. The regulators used used to include waterglass and/or inorganic phosphates. Waterglass had the disadvantage of leading to insoluble calcium silicate deposits being formed on the material and machinery, and the phosphates contributed to the eutrophication of effluents.
The polyphosphates which took their place are in turn very slow to biodegrade, if they do so at all, and thus are other kinds of water pollutants. Ethylenediaminetetraacetic acid (EDTA), which likewise does not biodegrade and in addition is not absorbed by the sewage sludge of a water treatment plant, is another water pollutant and is therefore undesirable for use as a bleach regulator; in addition, in the case of EDTA, it is not possible to completely rule out a remobilization of heavy metals, which are thus able to reenter the biological cycle. Phosphonobutanetricarboxylic acid regulators, too, have a very poor biodegradation rate. It is therefore desirable that EDTA, phosphonobutanetricarboxylic acids, polyphosphates and others only be used in minor amounts in formulations.
Hitherto it appeared to be very difficult to combine washing and bleaching, since the respective objectives and the auxiliaries consequently used are completely different. Furthermore, a very large amount of water is required on account of the two liquors required and the additional rinses. However, the desirable unification of the washing and bleaching processes appeared to fail because of the multiplicity of recipe ingredients required, since in practice it was impossible to rule out mistaken identities and incorrect dispensing, which ultimately led to an off-spec textile material which had to be retreated, thereby necessitating further large water quantities.
It has now been found that it is not just possible to combine the two operations, namely the operations of washing and of bleaching, but that it is also possible to avoid incorrect dispensing by using an inventive combination product of the below-described kind, and thereafter adding to the liquor only the alkali required for setting the pH and also the H.sub.2 O.sub.2 required.